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[Chemical Knowledge]：Production process and preparation method of dimethyl carbonate

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Dimethyl carbonate is an important chemical intermediate with wide application prospect. In the pharmaceutical, pesticide, paint, plastics and other industries, the demand for dimethyl carbonate is increasing. This article mainly introduces the production process and preparation method of dimethyl carbonate.

1. of dimethyl carbonate production process

At present, the production of dimethyl carbonate is mainly divided into two processes, namely phosgene method and coal gas method.

1. Production of dimethyl carbonate by phosgene

The production of dimethyl carbonate by phosgene is a process prepared by the reaction of phosgene and methanol. The specific process is as follows:

methanol phosgene → methyl carbonate

methyl carbonate methanol → dimethyl carbonate

The main advantage of this process is that the reaction process is very simple and the yield is high. However, phosgene is a toxic and harmful gas, which is easy to cause environmental pollution and safety hazards. Therefore, the process is only suitable for small-scale production.

2. Production of dimethyl carbonate by coal gasification

The production of dimethyl carbonate by coal gasification is a process prepared by the reaction of coal gas and methanol. The specific process is as follows:

gas oxygen → carbon monoxide carbon dioxide

carbon monoxide hydrogen → methanol

methanol CO2 → dimethyl carbonate

The main advantage of this process is that it can be produced using cheap coal resources, and at the same time it can be produced on a large scale. However, the process has many reaction steps and needs to be carried out under high temperature and high pressure, and the product purity is low and there is a certain degree of pollution.

2. The preparation method of dimethyl carbonate

The preparation method of dimethyl carbonate mainly includes the following:

1. Preparation of dimethyl carbonate

by phosgene method In the phosgene method, phosgene acts as a catalyst, so the catalyst needs to be placed in the reactor. In general, the reaction of methanol and phosgene needs to be carried out in a high temperature and high pressure atmosphere. The specific operation steps are as follows:

(1) Methanol, phosgene and catalyst are added into a reactor. The reactor was heated to 180-200 ° C. and pressurized to 5-7MPa

(2). The reaction

(3) is continued for 2-3 hours and the product is recovered by a condenser.

2. Preparation of dimethyl carbonate by coal-to-gas method

In coal-to-gas method, methanol and CO2 react to produce dimethyl carbonate. The specific operation steps are as follows:

(1) Methanol and CO2 gas are added into the reactor.

(2) according to a certain proportion of adding catalyst. The reaction temperature of

(3) is 200-350 ° C., and the reaction pressure is 2-4MPa.